Field of the Invention
The present invention relates to an image stabilizing apparatus, and more particularly to an image stabilizing apparatus configured to assist a user in a follow shot.
Description of the Related Art
A method using an image stabilizing apparatus has conventionally been proposed as a technology for assisting a user (photographer) in a follow shot.
Japanese Patent Laid-Open No. (“JP”) 2010-245774 discloses a technology for calculating an automatic release time period and an exposure time period based on at least one of the number of objects and the size of the object detected in a captured image in a follow shot image stabilizing mode.
JP 2006-317848 discloses a follow shot technology for detecting an angular velocity of an object based on a motion vector in an image and a blur detected by a gyro sensor, for calculating a correction amount for positioning the object at the image center based on the detected angular velocity, and for moving an optical axis shifting lens for the image stabilization.
JP 2007-336235 discloses a technology for classifying, through a histogram, motion vectors detected at feature points set to respective parts in an input image so as to discriminate an object from a background based on the motion vector in an image. JP 2007-336235 sets classification information representing a past classification result to each feature point and classifies the motion vector based on the classification information, when the motion vector obtained from a specific point is detected and the movement of the specific point is detected.
According to the prior art disclosed in JPs 2010-245774, 2006-317848, and 2007-336235, the calculated angular velocity of the object corresponds to a predetermined part of the object, but is not always a spot to be stopped by a photographer, because the angular velocity of the object does not always have a uniform value in angles of view. It is premised that the image stabilizing apparatus assists a follow shot of an object that provides a uniform linear motion. It is known that the object that provides the uniform linear motion does not have a constant angular velocity. FIG. 22 is a graph representing a relationship between the time and the angular velocity of the object that provides a uniform linear motion. As illustrated in FIG. 22, the angular velocity is maximum at time of 0. This means that a distance is minimum between the object and the photographer at time of 0, and an apparent velocity of the object is maximum since a locus of the object is orthogonal to a sight line of the photographer. As illustrated in FIG. 22, the angular velocity reduces with time. This means that a distance increases between the object and the photographer with time, and the apparent velocity of the object reduces. FIG. 23 illustrates an angle of view of the camera in a predetermined time period illustrated by a dotted line illustrated in FIG. 22. FIG. 23 is a graph representing a relationship between an image height and an angular velocity in an angle of view in a predetermined time period. The prior art uniformly sets a detecting position of a motion vector in the angles of view, discriminates the object from the background, and calculates the motion vectors of the object and the background by averaging the respective vectors irrespective of the image height. The angular velocity of the object calculated from the calculated motion vector may be an angular velocity at the center of the angle of view. For example, when the photographer sets a distance measuring position on the left side of the object, the distance measuring position is likely to be the very position at which the photographer would like to stop the object in the follow shot. In other words, the angular velocity of the distance measuring position is the position to be calculated as the angular velocity of the object. However, the prior art cannot calculate the angular velocity at the distance measuring position, and obtains an image having a blurred spot at which the photographer would like to stop. Moreover, the motion vector of the spot cannot be properly detected and thus the image blur increases, if the distance measuring position has a low contrast or contains a repetitive pattern.